The present invention pertains to secure satellite information transmission and more particularly to a method and system for over-the-air rekeying of a satellite.
A key is a piece of information which allows communication with a device such as a satellite. The longer one particular key is used for communicating with a satellite, the more susceptible that key is to being discovered and the satellite security compromised. Once discovered, unauthorized users may transmit information to the satellite. Therefore, it is necessary that this key information be periodically changed.
In addition, to the risk of being discovered, the key, if known to individuals, may be given to unauthorized users and, of course, the more people who know the key, the higher the probability of a human security breakdown. As a result, it is important to limit the human involvement in generating and distributing keys for accessing satellite communication links. If the keys are compromised, they must be changed or "rekeyed" on-board the satellite itself. Also, these keys should be changed on a periodic basis as a routine matter of security maintenance.
For expensive satellite programs employing a large number of satellites, the ability to change keys is especially important. The ways of rekeying large satellite systems are limited. Physical rekeying of such systems is impossible or at best impractical. Physical rekeying would entail either human or robotic contact with the satellite itself to input new keying information into the satellite.
A possible solution to this problem is to prestore multiple keys that are cued from a ground station or these prestored keys may be activated at particular times of the day or corresponding dates.
Another method for rekeying a satellite is to uplink new keys over existing or special, secure communication links. All of these solutions suffer from the shortcoming that they basically rely on frequencies, waveforms and codes that still fall into the category of information known by individuals which, if compromised, could be used by other unauthorized individuals. The human element eventually breaks down over time. If a satellite has a number of preprogrammed keys and all of these keys are compromised, the satellite must be reprogrammed (repaired in-orbit) or replaced. The cost of such reprogramming or replacement of vast satellite constellations of defense or commercial satellites is very great indeed.
Accordingly, it is an object of the present invention to provide a rekeying method and system for securely rekeying a satellite or other space platform based upon physical characteristics which are beyond human element breakdowns and which are as secure as a country's territory itself.